Due to their hydrophobic nature and low solubility in water, lipophilic active substances often exhibit poor bioavailability via the oral gastrointestinal (GI) delivery route. Furthermore, accurate and precise dosing is poor for drugs delivered via the GI system due to inherent variability caused by factors such as fasting state and first pass metabolism. As an alternative, pulmonary delivery using a dry powder inhaler (DPI) may be used. Traditional lactose-carrier (lactose blend) formulations for DPIs typically offer low drug loads, commonly less than 6% (wt/wt), and low delivery efficiencies (DE), typically delivering <30% of the drug to the lungs. Lactose blends are also highly flow rate dependent, showing significant variability with respect to aerodynamic performance. Once formulated, lactose blends rely on inter-particle forces to bind micronized drug to larger lactose carrier particles to maintain a uniform distribution of drug. This can present challenges during transportation and filling of powder into packages, which impart mechanical energy capable of redistributing or otherwise disturbing blend uniformity.
Engineered particles (e.g. spray dried) for DPIs offer significant improvements in drug payload, DE, good aerosol performance across a wide flow rates, and a lower risk for segregation of drug from excipients. However, lipophilic drug substances are challenging to encapsulate into dry, flowable, and dispersible powders that are compatible with dry powder inhalers. In addition, oils and fats exhibit poor dissolution and dispersion when incorporated into aqueous systems which are common in the preparation of annex solutions used to produce spray dried powders. This invention relates to new uses for terpenes as non-toxic, natural solubilizers for preparing vehicles (or annex solutions) which may then be spray dried to produce powders comprising various drugs, agricultural chemicals, cosmetics, and foods.